/*
 * Copyright (C) 2007-2008 Artima, Inc. All rights reserved.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Example code from:
 *
 * Programming in Scala (First Edition, Version 6)
 * by Martin Odersky, Lex Spoon, Bill Venners
 *
 * http://booksites.artima.com/programming_in_scala
 */

object Approximate {
  def isGoodEnough(guess: Double): Boolean = {
      println("guess [" + guess + "]")
      Math.abs(guess*guess - 2.0)  <  1.0E-6
  }

  def improve(guess: Double): Double =
      (guess + 2.0/guess)/2.0
      
  def approximate(guess: Double): Double = 
    if (isGoodEnough(guess)) guess
    else approximate(improve(guess))

  def approximateLoop(initialGuess: Double): Double = {
    var guess = initialGuess
    while (!isGoodEnough(guess))
      guess = improve(guess)
    guess
  }

  def main(args: Array[String]) {
    approximateLoop(3.3)
  }
}
